THE FIRST NOVEL in Len Deighton's new espionage trilogy was Berlin Game. Now comes Mexico Set and keener intellects than mine already will have anticipated a third novel to be called "Someplace-or-other-Match" -- thus completing what I suspect will be referred to as the tennis trilogy.

I confess that I didn't tumble to the game, set and match conceit until after finishing Deighton's entertaining second novel in this trilogy that again features fortyish Bernard Samson, the British spy who is afflicted with far more than the usual amount of both career and domestic difficulties.

But as in all trilogies, the problem is the back story. The author has to fill it in for those who haven't read the first novel without irritating those who have. Havin previously read Berlin Game, I wasn't at all bothered when Deighton again tells of Samson and his rich, beautiful, upper-middle- class wife, Fiona, who both work for the British secret intelligence service until . . . Well, I won't spoil the first book for those who want to start the series at the beginning.

Mexico itself doesn't provide much more than a routinely exotic locale and Deighton gives us a mere sidelong glance at it -- certainly not the long, cool, sometimes almost loving stare that he has turned time and again on Berlin and London and even Paris. Mexico is only a backdrop, a place where a passed-over KGB major might be approached by a British agent to see if he is interested in defecting to the West.

Bernard Samson was born into the spy trade. His father was head of Berlin Station for the British after World War II and saw to it that his son was reared and educated in the former German capital, thus providing us with a spy who virtually from the cradle on was indoctrinated in cold walore. In fact, Samson once describes himself as a "lapsed fascist."

But while Samson is traipsing around Mexico, his rivals back in London are jockeying for position in the spy bureaucracy. Suppose, it is murmured, that the traitor uncovered in Berlin Game fled East only to deflect suspicion from the real KGB mole who is still burrowing into the department? And who else could the real mole be but Bernard Samson?

Deighton manages to bring it all off nicely, as he usually does, writing with perhaps less sprightliness than in his previous novels, but with complete authority and control. When it comes to pitting working- class sharpies against Oxbridge twits, Deighton has few equals. He even gives us an American who has wormed his way up into the British spy hierarchy and is now lusting for a knighthood to show off back in the States. The American somehow is utterly believable.

Deighton also serves up fascinating glimpses of such types as rly senile head of British intelligence; a KGB major with a passion for Sherlock Holmes; and Samson's boyhood friend and Jewish orphan, Werner Volkmann, who managed to survive and even prosper in post-war Berlin, and now flits effortlessly back and forth between East and West.

However, it's Bernard Samson himself who deserves and gets both our attention and sympathy -- Samson with his problems of civil service pay, motherless children, a vengeance-bent wife, unsympathetic and even jealous superiors, and a job -- the only job he knows -- that could very well either kill him or land him in jail.

We go from Mexico to London to Berlin and on to Paris in this novel about greed and deceit and treachery, which are the essential ingredients of all good thrillers. And once again Deighton has woven an intricate and wholly satisfying plot, peopled it with convincing characters, and even managed to give a new twist or two to the spy story. But then he is a master of the form, and Mexico Set is one of his better efforts.

Game. Set. And match. I now can't help but wonder where match will be set. CAPTION: Picture, Len Deighton. Photo copyright (c) by Paul Kanvanagh